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Head gasket voodoo
Here is the set-up. 351W, Ford J302 alum heads, Felpro1011-2 gasket, ARP 170,000 bolt with ARP moly. Very careful assembly with proper torque sequence in 20lb. increments to 75ft.lbs as per ARP. Water leaks between block and gasket before start up right side only. I remove head and find water marks uniformly around each passage. Gasket shows NO! sign of compression anywhere. The blue silicone bead in the gasket looks new no head imprint anywhere. Have head and block checked and both are true which fits with headgasket looking new. Hand thread each bolt into block measure length-no prob. Reassemble and get the the same result. Increase torque to 85 [iron head spec] and seapage stops. Cross fingers and have an uneventful break in. Next morning retorque-loosen bolt 1/4 turn reset to 75. Some bolts are barely tight some loosen with a loud crack all take up an extra 1/4to1/2 turn just to get to 75. Other than someone stealing a lock of my hair making a doll what is the explanation?:confused: Now if I can just get a new pan from Milodon I may make it to Willow for the COCOA event:3DSMILE:
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Slide,
Are you sure ARP sent you the correct length head bolts? Sounds like you're running into thread engagement problems in the engine block. Did you chase the threads before installing the heads? What lubricant are you using on the head bolts? Did you check if you had adequate thread depth in all the holes by screwing them in with the heads off? If you removed the heads and the head gaskets were not compressed, you are running out of threads before the bolts can pull the head into proper contact with the block. Mike |
Mike, the answer is yes to all the above which is why voodoo seems most likely. I hand threaded each bolt into the block and measured the amount left. I was not bottoming out. I used ARP moly on the washers and bolthead and ARP teflon thread sealer on the threads. I even used a second washer after the first water leak just to be sure but it did not help. If I had bottomed out an extra 10ft. lbs would not helped and I could not have taken up another 1/4to1/2 turn on the retorque. I actually don't think I will have any future problems with it, I just can't figure out what happened.
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Is it possible that the head was sitting on the alignment pins and then squashed down all the way?
Ed |
Ed, that's a good thought but they seemed to slip into the block and heads smoothly and showed no sign of damage on removal.
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Slide:
I came by today but, apparently you were somewhere else or didn't hear the bell. I saw you still had the engine on the stand so I knew all was not well. Try this 1. Put the head on the block with NO gasket. 2. One at a time put in each bolt and see if it tightens the head up. Remove the bolt and try the next one. This might be informative!! I'm running at Buttonwillow tomorrow :) ,but will try to stop by on Sunday sometime if you are going to be home. John W. |
Head Gasket Blues
It sounds like the either the block face or the cylinder head faces have had a significant amount of material removed therby reducing the depth of the machined alignment dowel holes on the faces of the block and head. If you have dial calipers, measure the the depth of the machined receiver in each face plus thickness of head gasket, this dimension should be greater than the length of the dowel itself.If this checks out, you may be running out of thread as you clamp the head down, be sure you have the correct bolts/studs. Lastly if you are running domed pistons be sure the deck height is set right.
No room for error here.........good luck Rick............... |
Thanks Rick, but the reciever in the heads is deep enough to swallow the entire dowel pin and then some. I am useing flat top pistons. When I finally get a replacement pan[first one was warped] I'll put it back on the brake-in stand and make sure no more wierdness before reinstalling in the car.
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Clyde,
Sorry to hear you are still having problems. Sounds like you have checked every possible area that could have hung the head up. Keep that voodo doll away from me!!! You haven't pissed any patient's off recently have you???? Good luck, Steve |
clyde, just a guess. I wonder if the pistons/rod geometry is wrong. If the piston at the top of the chamber is above the deck slightly, you will hit it when you torque the head bolts. I have seen this one first hand. good luck, scott
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Also thinking alignment dowels. If the block deck is flat, and the head is flat, and pistons aren't sticking up over zero deck in the bore, then the alignment dowels are the only thing the head can hang on. Try opening up dowel holes in head one drill size (1/64"), then make sure there's enough depth in the dowel hole in the head to take the entire depth of the dowel above the block plus 1/32" without the head gasket in place. Then take a 45 degree chamfering tool and chamfer the dowel hole in the head, just enough to deburr it.
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Thanks all, the rods are stock and the pistons are below the deck at tdc. The alignment dowels must be it because I think I've eliminated everything else but I know I have room for them. We will see what happens at the next start-up. Steve, hope the paint shop is on track, I am real interested your progress.
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Clyde,
Of course the paint shop is not on track. That would make my life too easy. My friend finally got his shop moved and open three months late. The car has now been in storage in his shop for two weeks. Hindsight is twenty-twenty, I probably should have sent it elsewhere else in January. I would probably be on my final assembly now. The engine is very close to being done, provided I do not have any Gremlins of significance. Will your heads sit flush down on the block without the head gasket in place? Hope you get the pan soon, Steve |
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